1. Field of the Invention
This invention relates to a disk clamp device, equipped in a recording-reproducing device, for clamping a disk to give turning force thereto.
2. Description of the Prior Art
Various kinds of information processing devices recently marketed are employing a recording-reproducing device utilizing magnetism. The recording-reproducing device operates in such a manner that after a disk ( a flexible magnetic disk, for example ) is placed on a spindle, this spindle is drivent o rotate the disk. While it is rotating, a magnetic head is positioned as to oppose to a recording face of the disk and recording/reproducing of information is performed.
As the disk clamp device being employed in such recording-reproducing devices, an arrangement as shown in FIGS. 5 and 6 has been proposed in the prior art. FIG. 5 is a sectional view of the disk clamp device at the time of insertion of the disk, and FIG. 6 is a plane view of a clamp member included in this disk clamp device. Incidentally, this disk clamp device is assembled in the recording-reproducing device for driving the magnetic disk.
In these drawings, the symbol 5 indicates a base frame. On this base frame 5 a spindle 1 coupled to a motor ( not shown ) is supported via a bearing 6. To the upper end of this spindle 1 a turntable 7 is fixed. In the center of this turntable 7 a concave portion 7a is formed around the spindle 1. On the upper face 7a of this turntable 7 a flexible magnetic disk 2 is placed. For reference, the diameter of this concave portion 7a is substantially equal to the diameter of a drive shaft insertion hole ( not shown ) bored at the center of the magnetic disk 2.
The symbol 3 indicates a frame. This frame 3 is pivoted in the arrow A directions in FIG. 5 and opposes approach-/separate-ably to the turntable 7. This frame 3 has a hole 3a bored therein, through this hole 3a a shaft 4 passes, this shaft 4 is smaller in diameter than the hole 3a, thus, the shaft 4 is allowed to move in radial directions within the hole 3a. At the upper end of the shaft 4 a snap 8 is fitted. This snap 8 is stopped by the upper face of the frame 3 via a washer plate 9, so that the shaft 4 is prevented from coming off. To the lower end of the shaft 4 a clamp member 11 is attached via a bearing 10.
This clamp member 11 is made of resin and molded integrally, in its center a hole 12 is bored, and at a lower portion of this hole 12 a projection 13 is provided circularly facing the inside of the hole 12. The bearing 10 force-fitted in the hole 12 is stopped by the projection 13 and fixed there. Further, a flange 4a formed at the lower end of the shaft 4 is brought to the hole ( 12 ) portion underside the projection 13, and this flange 4a is stopped by the projection 13. From the whole upper periphery of the hole 13 an arm portion 14 is extending outward. The points of this arm portion 14 are curved downward. Press portions 15 are formed on the end faces of the curved point portions. That is, to the upper faces of these press portions 15 the points of the arm portion 14 are connected. The lower end of each press portion 15 defines a flat press face 15a. This press face 15a is opposing to the upper face 7b of the turntable 7. To the inside of this press portion 15 one end of a guide portion 16 is joined. In all, a number of paired guide portions 16 are provided along the inner periphery of the press portions 15 with an equal spacing. Further, in the arm portion 14 there are formed relief holes or slits 17 to bring the respective guide portions 16 up from a die in the molding process. Each guide portion 16 is composed of an engaging face 18 extending vertically downward from the inside of the press portion 15 and a guide face 19 further extending obliquely inward from the lower end of the engaging face 18, and is molded so as to have a relatively thin thickness to exhibit flexibility. The diameter D1 of the engaging faces 18 is designed as to be larger a little than the inner diameter D2 of the concave portion 7a of the turntable 7. Thus, the engaging faces 18 can fit tightly in the concave portion 7a with some elastic deformation. The symbol 11a indicates a reinforcing rib for supporting the arm portion 14. A compression spring 20 is interposed between the bearing 10 force-fitted in the hole 12 of the clamp member 11 and the inner face of the frame 3.
Now, the operation of the disk clamp device of the foregoing structure proposed in the prior art will be described.
In the initial state, the frame 3 is raised beforehand by means of a spring and the like ( not shown ). In this position, the clamp member 11 is pushed by the compression spring 20 via the bearing 10, and the projection 13 formed inside the hole 12 is stopped by the flange 4a formed on the shaft 4, so prevented from coming off.
The magnetic disk 2 is inserted in the arrow B direction shown in FIG. 5 through an insertion opening ( not shown ) of the recording-reproducing device, and a drive shaft insertion hole ( not shown ) of the magnetic disk 2 is brought above the concave portion 7a of the turntable 7. Thereafter, the frame 3 is pivoted manually or by other means to go down. In response thereto, the clamp member 11 approaches gradually the turntable 7. Then, the lower end of each guide face 19 of the clamp member 11 passes first through the drive shaft insertion hole of the magnetic disk 2 and is brought within the concave portion 7a of the turntable 7. During the above movement, the peripheral margin of the drive shaft insertion hole of the magnetic disk 2 contacts slidingly with each guide face 19, and the magnetic disk 2 is pushed in radial directions. Concurrently therewith, if the shaft 4 is displaced axially with respect to the spindle 1, the guide faces 19 are guided by the concave portion 7a of the turntable 7 and their axial centers are made harmonized. In this way, during the downward movement of the clamp member 11, the center of the magnetic disk 2 is gradually brought on the axis of the spindle 1 ( the provisional centering ). When the engaging faces 18 of the clamp member 11 are brought within the concave portion 7a of the turntable 7, because the diameter D1 of the engaging faces 18 has the relation, D1&gt;D2, in connection with the diameter D2 of the concave portion 7a, the engaging faces 18 are guided by the peripheral margin of the concave portion 7a and deforms elastically inward. During the above, the drive shaft insertion hole of the magnetic disk 2 is pushed by the engaging faces 18 and forms the concentric circles with the inner diameter D2 of the concave portion 7a, thus, the subject centering is completed. Concurrently therewith, the press faces 15a of the press portions 15 formed on the clamp member 11 approach the upper face 7b of the turntable 7. Then, when the press faces 15a abut on the upper face 7b of the turntable 7 via the magnetic disk 2, the clamp member 11 terminates its lowering. Then, as the frame 3 goes down further, the compression spring 20 is pressed, this pushing force is transmitted through the bearing 10 and the projection 13 of the clamp member 11 to the arm portion 14. Thus, this arm portion 14 pushes the press portions 15 from above. As a result, the press faces 15a push the magnetic disk 2 evenly onto the upper face 7b of the turntable 7. Thus, the magnetic disk 2 is secured surely on the upper face 7b of the turntable 7. Then, as the frame 3 reaches the bottom dead point, its lowering action terminates and the centering and clamping operation of the magnetic disk 2 is completed.
Following the above, as the spindle 1 in the stopped state is driven the magnetic disk 2 starts to rotate, and the magnetic head ( not shown ) opposing to the recording face of the magnetic disk 2 is permitted to perform reading/writing of information.
As the frame 3 is pivoted as to rise, the clamp member 11 is returned to its initial state by the recoil strength of the compression spring 20.
However, not that the foregoing prior art has no problem. Recently, the recording-reproducing device for driving the magnetic disk has a tendency to become small in size, and, in connection therewith, the pivotable angle of the frame 3 of the disk clamp device is becoming limited small. Accordingly, as shown in FIG. 5, the possibility that at the time of insertion of the magnetic disk 2 its point portion may abut and catch on the point of some guide portion 16 of the clamp member 11 is becoming increasing. Thus, due to such catching, smooth insertion of the magnetic disk 2 is disturbed, the magnetic disk 2 suffers plastic deformation in case the disk is housed in a soft case to give a bad influence to the recording-reproducing property, or some guide portion 16 of the clamp member 11 suffers plastic deformation in case the magnetic disk 2 is housed in a hard case to result in an uncertain clamping of the disk.